Pulley construction

ABSTRACT

A pulley for use in a belt drive assembly. The outer surface of the pulley is divided into high friction portions which are in frictional engagement with the belt and low friction portions where the belt has little or no driving engagement with the pulley. The effective or belt-engaging areas of the high and low friction portions are proportioned to obtain a driving relationship with the belt under normal load conditions but to slip under overload conditions.

[ 1 Aug. 8, 1972 United States Patent Brooks et al.

[54] PULLEY CONSTRUCTION Primary Examiner-Leonard H. Gerin Harold W.Attomeyl-libben, Noyes & Bicknell w m QC .C m m m m d mr. u m u flt h msm m m J& Nfi t. n m z n m m N no r 1 1 A pulley for use in a belt driveassembly. The otiter surface of the pulley is divided into high frictionportions which are in frictional engagement with the belt [22] Filed:April 29, 1970 PP N04 32,844 and low friction portions where the belthas little or no driving engagement with the pulley. The effective orbelt-engaging areas of the high and low friction portions areproportioned to obtain a driving relationship with the belt under normalload conditions but to slip under overload conditions.

' l2 Clains, 13 Drawing figures [56] References Cited UNITED STATESPATENTS 468,843 2/1892 St. John......... .....74/230.0l

hummus elm 3,682,010

SHEET 1 BF 3 Joseph flBraoks, Harold W. 5 c/zgefen minnows 19123,682,010

SHEEI 2 BF 3 IIIIIl/m Inveniora: Jb 5922b F5 rooks,

Harold WSchaefer; 9 W

PULLEY CONSTRUCTION Belt drives are of course well known and commonlyused to rotatably couple a drive motor to a device to be driven. Such anarrangement includes a drive pulley connected to the power output shaftof the drive motor, a driven pulley connected to the driven device, anda belt coupling the two pulleys. The diameters of the drive and drivenpulleys are proportioned to produced a desired speed ratio.

In such an arrangement, a problem arises where the driven device issubject to being heavily overloaded or jammed, resulting in the drivenpulley either slowing down or stopping entirely. Where the driven pulleyhas a larger diameter than the drive pulley to obtain a speed reduction,it has been found that the belt may be damaged or destroyed by the drivepulley in such circumstances. This is due to the fact that the area ofcontact between the belt and the driven pulley is large as compared withthe area of contact between the belt and the drive pulley, resulting inthe belt having greater frictional engagement with the driven pulleythan with the drive pulley. Consequently, when the driven pulley isstopped, it holds the belt against turning while the drive pulleycontinues to turn. The rapidly turning drive pulley rubs against thebelt and may quickly generate enough heat to damage the belt by meltingit. Use of an ordinary friction clutch has proven to be unsatisfactorybecause they usually wear or burn out when used frequently over a longperiod of time.

In accordance with the present invention the foregoing problem iseliminated by providing a clutch pulley having its outer belt contactsurface divided into high friction portions and low friction portions.The total area of the high friction portions is proportioned relative tothe total area of the low friction portions to obtain sufficienttractive effort or force to drive the driven device under normal loadconditions but to enable the belt to slip on the pulley under overloadconditions. The diameter of the belt contact surface of the clutchpulley is sized to provide a desired speed ratio.

Objects and advantages of the invention will become apparent from thefollowing detailed description taken in conjunction with theaccompanying figures of the drawings, wherein:

FIG. 1 is a perspective view of a vacuum cleaner including a clutchpulley embodying the invention;

FIG. 2 is an enlarged view of the vacuum cleaner with the hood thereofremoved to show internal parts;

FIG. 3 is an enlarged perspective view showing a rotating brush assemblyof the vacuum cleaner;

FIG. 4 is an enlarged fragmentary sectional view taken on the line 44 ofFIG. 2;

FIG. 5 is an enlarged view showing a clutch pulley embodying theinvention;

FIG. 6 is a sectional view taken on the line 6-6 of FIG. 5;

FIG. 7 is an exploded view showing parts of the clutch pulley;

FIG. 8 is a view generally similar to FIG. 1 but illustrating a cleanerincluding a clutch pulley in accordance with an alternate form of theinvention;

FIG. 9 is a view generally similar to FIG. 2 but showing the cleaner ofFIG. 8;

FIG. 10 is a fragmentary enlarged exploded view showing the alternateform of pulley;

FIG. 11 is another view showing the alternate form of the pulley;

FIG. 12 is a view taken on the line l212 of FIG. 11; r

and

FIG. 13 is a sectional view taken on the line 13-13 of FIG. 12.

While the clutch pulley is described herein in connection with a drivefor a rotating brush of a vacuum or suction cleaner, it should beunderstood that it also has wide use in other fields. Further, althoughthe clutch pulley described herein is used as a driven pulley, it shouldbe understood that it also has use as a drive pulley.

With reference to the drawings, FIGS. 1 and 2 illustrate a suction orvacuum cleaner of the upright type, including a hood 20 coveringinternal parts of the machine, a handle 21 for moving the cleaner acrossthe floor, a cord reel holder 22 attached to the handle for storing alength of electric cord 23, and a filter bag support 24 also attached tothe handle. One end of the electric cord 23 extends into the interior ofthe hood 20 and is connected to a motor-fan unit 26. The other end ofthe electric cord 23 has a conventional plug 27 attached thereto forconnecting the motor-fan unit 26 to .an electric outlet. A clip or cordholder 28 may be attached to the handle 21 for holding the plug 27 whenthe cleaner is not in use, and an on-off switch 29 may be mounted on theupper end of the handle 21 for the convenience of the operator inturning the motor-fan unit 26 on and off. Wheels 30 (FIG. 2) areprovided for moving the cleaner across the floor during operation.

With reference to FIG. 2, the cleaner further includes a frame 31, themotor-fan unit 26 and the wheels 30 being fastened to the frame.Rotatably mounted on the frame is a rotating brush assembly 36, shown ingreater detail in FIG. 3. The brush assembly 36 includes a shaft 37which is supported at its ends by brackets 38 (FIG. 2) adjacent theforward side of the frame 31. The shaft 37 extends down the center ofand rotatably supports a cylindrical roll 42, and bristles 43 aresecured to and extend outwardly from the outer surface of the roll 42. Aclutch pulley 44, to be described in greater detail hereinafter, issecured to the roll 42 intermediate its ends. An arcuate cover orhousing 41 is positioned over the brush assembly 36 and fastened to theframe 31 by screws 40, as shown in FIG. 2. The frame 31 has an elongatedopening 39 (FIGS. 1 and 2) formed therein below the brush assembly 36,and the bristles 43 extend into the opening 39 when the assembly 36 isrotated during operation of the cleaner. A duct or dirt passage 45connects the interior of the housing 41 to an air intake 47 of themotor-fan unit 26, the unit 26 further including an outlet 48 which isconnected to a filter bag located in the bag support 24.

In addition to driving a fan, the motor of the unit 26 is also connectedto drive the brush assembly 36 during operation of the cleaner. Thedrive connection includes a drive pulley 51, the clutch pulley 44, and abelt 52 (FIGS. 1, 2 and 4). The drive pulley 51 is secured to the driveshaft 53 of the motor in the unit 26, and the belt 52 extends throughthe dirt passage 45. The drive motor normally rotates at much higherspeed than it is desirable for the brush assembly to rotate, andconsequently the diameter of the drive pulley 51 is made smaller thanthe diameter of the clutch pulley 44, as shown in FIG. 4, in order toeffect a speed reduction.

During operation of the cleaner, the motor-fan unit 26 is energized byconnecting the plug 27 in an electrical outlet and turning on the switch29. The motor of the unit 26 drives the fan and also rotates the brushassembly 36. The fan creates a suction within the housing 41, suchsuction drawing dirt particles from a rug being cleaned upwardly throughthe opening 39, through the 5 dirt passage 45, and out of the outlet 48to the filter bag. The rotating brush assembly 36 serves to disturb anddislodge dirt particles so they can be drawn upwardly by the suction ofthe cleaner.

During such operation of the cleaner, it frequently 1 ciently long thatthey extend beyond the outer surfaces of the two sections 63 and 64.With reference to FIG. 5, the extended portions of two of the pins 62are indicated by the reference numeral 81. Holes, located in alignmentwith the extensions 81, are formed in the adjoining surfaces of the twosegments of the roll 42, the holes in the segments receiving theextensions 81 and thus preventing the clutch assembly from turningrelative to the roll 42.

To maintain the clutch pulley 44 centered in the brush assembly, acentral hole 82 (FIGS. 4 and 6) is formed through the main body 60 andthe segments of the roll 42 including telescoping tubular portions 83and 84 (FIG. 4) which extend around the shaft 37 and speed.Consequently, in a cleaner having a conventhe clutch pulley 44. Thepulley 44 comprises a main body which is generally circular in crosssection, (FIGS. 4 to 6), a plurality of rollers 61 and a plurality ofpins 62. The main body 60 includes a pair of identical sections 63 and64 which, when assembled, are in butting relation along the lineindicated by the numeral 66 in FIG. 5. Each of the sections 63 and 64includes a side wall 67 and a tapered portion 68, the wall 67 having alarger diameter than the portion 68, and the taper of the portion 68being radially outwardly and away from the wall 67. Due to the tapers ofthe portions 68, the main body 60 has a crowned configuration betweenthe two side walls 67, as shown in FIG. 5. This crowned configuration isused with a flat belt having a width less than the distance between thetwo walls 67, the crown serving to maintain the belt at substantiallythe center of the pulley as shown in FIG. 2.

With particular reference to FIGS.- 4 and 6, the two sections 63 and 64have a plurality of arcuate cavities 71 formed therein, the cavities 71opening to the outer surfaces of the sections. Longitudinally extendingholes 72 are formed through the two end walls 67 in alignment with thecenter of each cavity 71, and each of the holes 72 is counterbored, asindicated at 73, at its inner end.

With reference to FIG. 7, each of the rollers 61 has a crowned centralportion, indicated at 74, and two end walls 76. The crowned portion 74has essentially the same configuration and length as the crowned portionof the main body 60 as shown in FIG. 5, and the end walls 76 are sizedto fit entirely within the counterbores 73. One of the pins 62 ispositioned through an axial hole 77 formed through each roller 61, thepins being sufficiently long to extend into the holes 72 in the walls67, thus rotatably supporting a roller 61 in each cavity 71.

The clutch pulley assembly may be fastened to the remainder of the brushassembly 36 by any suitable means. In the present instance, the roll 42is formed in two segments and the clutch pulley is located between thetwo segments. The clutch pulley is fastened to the two segments bymaking some or all of the pins 62 suffiinto the hole 82 in snug-fitrelation therewith.

As best shown in FIG. 4, the belt 52 engages the outer surfaces of theportions 85 of the main body 60, between the cavities 71, and the outersurfaces of the rollers 61. Tractive effort or torque is exerted by thebelt 52 on the portions 85, and these portions are referred to herein ashigh friction portions of the clutch pulley. Since'the rollers 61 arefreely rotatable on the main body 60, little or no tractive effort isexerted on them by the belt 52, and the area represented by the outersurfaces of the rollers is referred to herein as low friction portionsof the clutch pulley. The

outer surface areas of the high friction portions 85 are proportioned,relative to the outer surface areas of the low friction portions, toproduce sufficient torque to turn the brush assembly during operation ofthe cleaner. However, in the event the brush assembly is jammed, the.lowfriction portions comprising the rollers 61 enable the belt to turnrelative to the main body 60, thereby preventing the drive pulley 51from burning out the belt 52. In the construction illustrated, the highfriction portions 85 comprise approximately onehalf the total beltengaging surface of the pulley. As previously mentioned, the contour ofthe rollers 61 is substantially the same as that of the portions 85 ofthe main body 60, and such construction is desirable because it reducesflexing of the belt as the belt passes over the rollers and the portions85. While the clutch pulley might be operative without the rollers 61,their presence is desirable because they provide surface continuitybetween adjacent high friction portions 85 and thus reduce flexing ofthe belt. The rollers also reduce the pressure per unit area by the belton the portions 85 and thus enable the belt to slide on the portions 85.While the belt will slide on the portions 85 when the brush assembly isjammed and generate some heat, the relatively large pulley 44 forms anexcellent heat sink and thus prevents damage to the belt 52.

The clutch pulley need not, of course, be fastened to a driven deviceintermediate the ends thereof as shown in FIGS. 1 to 7. FIGS. 8 through13 illustrate a construction including agenerally similar clutch pulley,wherein the pulley is fastened to an end of a brush assembly of acleaner. The cleaner shown in FIGS. 8 and 9 is generally similar to thatshown in FIGS. 1 and 2, and includes a hood 91, a handle 92, a filterbag holder 93 and a cord reel holder 94. The cleaner further indrivesthe belt 97, and a clutch pulley 101 is fastened to one end of the brushassembly 98. A cover 102 is positioned over the brush assembly 98 andincludes an outlet 103 which is connected by a duct (not shown) to afilter bag in the holder 93. The brush assembly 98 is rotatablysupported on the frame of the cleaner by brackets 104 (FIG. 9), and acentrally located shaft 106 of the brush assembly 98 supports the brushassembly on the brackets 104.

As shown in FIG. 10, one end of the shaft 106 is threaded and the clutchpulley 101 is screwed on this end. The clutch pulley 101 includes a mainbody 107, a plurality of rollers 108, and a plurality of pins 109 whichsupport the rollers 108 on the body 107. Formed in the main body 107 area plurality of equally spaced arcuate cavities 111 which are similar tothe cavities 71. The outer surface portions 112 between the cavities 111 are referred to herein as high friction portions. The rollers 108 aresupported by the pins 109 in the cavities 111 and are referred to hereinas low friction portions of the clutch pulley. The rollers 108 and themain body 107 have similar contours. The pulley 101 is also designed foruse with a flat belt and therefore both the rollers 108 and the portions1 12 have crowned configurations. As shown in FIG. 12, neither the mainbody 107 nor the rollers 108 includes radially extending side wallscorresponding to the walls 67 and 76 of the pulley 44.

To facilitate manufacture of the main body 107 and assembly with thepins 109 and rollers 108, the main body 107 is comprised of two partswhich are fastened together by screws 1 13 (FIG. 13). One part of themain body 107 is indicated by a reference numeral 116 and comprises theremainder of the main body 107, the two parts 114 and 116 abutting alongthe line indicated by the reference numeral 117 in FIG. 12. Internallythreaded and countersunk holes are formed in the seg ments 114 and 116for the screws 113. To fasten the clutch pulley 101 to the shaft 106, anaxially located, internally threaded hole 121 is formed through theclutch pulley 101, which is screwed on the threaded end of the shaft106.

The operation and advantages of the pulley illustrated in FIGS. 8through 13 are similar to the pulley illustrated in FIGS. 1 through 7,the differences between the two constructions being the location of thepulley on the brush assembly and the manner in which the pulleys areconnected to the brush assembly, and the fact that the clutch pulleyillustrated in FIGS. 8 through 13 does not include side walls.

While the clutch pulleys illustrated and described herein are designedfor use with a flat belt, it will be apparent that clutch pulleysembodying the invention may be designed for use with round belts or Vbelts. When used with a round or a V-belt, the portions of the pulleywhich are engaged by the belt are curved or dished inwardly to match theshape of the belt, rather than crowned as illustrated in the drawings.In any construction, the relative areas of the high and low frictionportions of the the clutch pulley are proportioned to provide sufficienttractive effort to turn the device being driven while at the same timeenabling the belt to slip on the pulley in the event the device beingdriven is stopped for any reason. The amount of tractive effort exertedby the belt on the clutch pulley is determined by the relative areas ofthe high and low friction portions, their radial dimensions, the tensionon the belt,

and the circumferential spacing between adjacent low friction portionsand adjacent high friction portions. As previously mentioned, a clutchpulley as described herein is not limited in its use to a suctioncleaner but may be used in numerous other fields. While a clutch pulleyembodying the invention may be used as a drive pulley rather than as adriven pulley, it is preferably used as a driven pulley because it canbe made relatively large to obtain a speed reduction and, at the sametime, it can be constructed to slip during overload conditions. Whilethe clutch pulley has been described as being advantageous in situationswhere flexibility in the amount of torque delivered is desirable, it mayalso be used where shock reduction is desired. 1

We Claim:

1. A clutch pulley for use in a drive assembly includ ing a belt and acooperating pulley, said clutch pulley comprising a generally circularmain body including a plurality of relatively high friction means on theouter surface thereof, said high friction means being circumferentiallyspaced around the periphery of said main body and being adapted to beengaged by said belt, and a plurality of members rotatably mounted onsaid main body and adapted to be engaged by said belt, one of saidmembers being located in each of the spaces between said spaced highfriction means.

2. A clutch pulley as in claim 1, wherein said high friction meanscomprises circumferentially spaced outer surface portions of said mainbody.

3. A clutch pulley as in claim 1, wherein a plurality of cavities areformed in said main body between said high friction means, said membersbeing mounted in said cavities.

4. A clutch pulley as in claim 1, wherein each of said members comprisesa roller rotatable mounted on said main body.

5. A clutch pulley as in claim 4, wherein said rollers and said highfriction means have generally similar outer contours.

6. A clutch pulley as in claim 5, wherein said rollers and said highfriction means have crowned contours.

7. A clutch pulley as in claim 1, wherein said high friction meanscomprises circumferentially spaced outer surface portions of said mainbody, and said outer surface portions are separated by cavities formedin said main body, said members being mounted in said cavities.

8. A clutch pulley for use in a drive assembly including a belt and acooperating pulley, said clutch pulley comprising a generally circularmain body, high friction means on the outer periphery of said body, saidhigh friction means including a plurality of circumferentially spacedportions, and low friction means on the outer surface of said main body,said low friction means including a plurality of members rotatablymounted in the spaces between said circumferentially spaced portions,said high and said low friction means having similar outer contours andboth being adapted to be engaged by said belt.

9. A clutch pulley as in claim 8, wherein the total area of said highfriction means is proportioned relative to the total area of said lowfriction means to obtain sufficient tractive effort for the belt todrive said clutch pulley under normal load conditions but to enable saidbelt to slip under overload conditions.

10. A clutch pulley comprising a generally circular main body, aplurality of circumferentially spaced arcuate cavities formed in of saidbody, the axes of said cavities extending generally parallel to andbeing radially spaced from the axis of said main body, and a pluralityof rollers, one of said rollers being rotatably mounted in each of saidcavities, the outer surface portions of said body between said cavitiesforming high friction portions and said rollers forming low frictionportions, and the outer contours of said outer surface portions and saidrollers being generally similar.

11. A clutch pulley as in claim 10, wherein each of said rollers isrotatably supported on said body by a pin.

12. A clutch pulley as in claim 10 wherein said main body includes apair of sections and means for securing said sections together, saidsections being separable along a generally radially extending plane, oneend of each of said rollers being supported by one of said sections andthe other end of each of said rollers being supported by the other ofsaid sections.

1. A clutch pulley for use in a drive assembly including a belt and acooperating pulley, said clutch pulley comprising a generally circularmain body including a plurality of relatively high friction means on theouter surface thereof, said high friction means being circumferentiallyspaced around the periphery of said main body and being adapted to beengaged by said belt, and a plurality of members rotatably mounted onsaid main body and adapted to be engaged by said belt, one of saidmembers being located in each of the spaces between said spaced highfriction means.
 2. A clutch pulley as in claim 1, wherein said highfriction means comprises circumferentially spaced outer surface portionsof said main body.
 3. A clutch pulley as in claim 1, wherein a pluralityof cavities are formed in said main body between said high frictionmeans, said members being mounted in said cavities.
 4. A clutch pulleyas in claim 1, wherein each of said members comprises a roller rotatablemounted on said main body.
 5. A clutch pulley as in claim 4, whereinsaid rollers and said high friction means have generally similar outercontours.
 6. A clutch pulley as in claim 5, wherein said rollers andsaid high friction means have crowned contours.
 7. A clutch pulley as inclaim 1, wherein said high friction means comprises circumferentiallyspaced outer surface portions of said main body, and said outer surfaceportions are separated by cavities formed in said main body, saidmembers being mounted in said cavities.
 8. A clutch pulley for use in adrive assembly including a belt and a cooperating pulley, said clutchpulley comprising a generally circular main body, high friction means onthe outer periphery of said body, said high friction means including aplurality of circumferentially spaced portions, and low friction meanson the outer surface of said main body, said low friction meansincluding a plurality of members rotatably mounted in the spaces betweensaid circumferentially spaced portions, said high and said low frictionmeans having similar outer contours and both being adapted to be engagedby said belt.
 9. A clutch pulley as in claim 8, wherein the total areaof said high friction means is proportioned relative to the total areaof said low friction means to obtain sufficient tractive effort for thebelt to drive said clutch pulley under normal load conditions but toenable said belt to slip under overload conditions.
 10. A clutch pulleycomprising a generally circular main body, a plurality ofcircumferentially spaced arcuate cavities formed in of said body, theaxes of said cavities extending generally parallel to and being radiallyspaced from the axis of said main body, and a plurality of rollers, oneof said rollers being rotatably mounted in each of said cavities, theouter surface portions of said body between said cavities forming highfriction portions and said rollers forming low friction portions, andthe outer contours of said outer surface portions and said rollers beinggenerally similar.
 11. A clutch pulley as in claim 10, wherein each ofsaid rollers is rotatably supported on said body by a pin.
 12. A clutchpulley as in claim 10 wherein said main body includes a pair of sectionsand means for securing said sections together, said sections beingseparable along a generally radially extending plane, one end of each ofsaid rollers being supported by one of said sections and the other endof each of said rollers being supported by the other of said sections.